C Shell
tcsh and sh side-by-side on a Mac OS X desktop.
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| Original author(s) | Bill Joy |
|---|---|
| Initial release | 1978 |
| Stable release |
6.20.00 / November 24, 2016
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| Repository | bxr |
| Written in | C |
| Operating system | BSD, UNIX, Linux, Mac OS X |
| Type | Unix Shell |
| License | BSD license |
The C shell (csh or the improved version, tcsh) is a Unix shell created by Bill Joy while he was a graduate student at University of California, Berkeley in the late 1970s. It has been widely distributed, beginning with the 2BSD release of the Berkeley Software Distribution (BSD) that Joy began distributing in 1978. Other early contributors to the ideas or the code were Michael Ubell, Eric Allman, Mike O'Brien and Jim Kulp.
The C shell is a command processor typically run in a text window, allowing the user to type commands. The C shell can also read commands from a file, called a script. Like all Unix shells, it supports filename wildcarding, piping, here documents, command substitution, variables and control structures for condition-testing and iteration. What differentiated the C shell from others, especially in the 1980s, were its interactive features and overall style. Its new features made it easier and faster to use. The overall style of the language looked more like C and was seen as more readable.
On many systems, such as Mac OS X and Red Hat Linux, csh is actually tcsh, an improved version of csh. Often one of the two files is either a hard link or a symbolic link to the other, so that either name refers to the same improved version of the C shell.
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